Electric lawn mower with improved grounding means



l- JEPSON Nov. 16, 1965 ELECTRIC LAWN MOWER WITH IMPROVED GROUNDINGMEANS //\/\/EN7'OE M42 JEP50A/ fieagz K K 64 ATTORNEY Original Filed May28, 1956 3,217,824 ELECTRIC LAWN MOWER WITH IMPROVED GROUNDING MEANSIvar Jepson, 547 Linden Ave., Oak Park, Ill. Application July 6, 1959,Ser. No. 825,255, now Patent No. 3,028,719, dated Apr. 10, 1962, whichis a division of application Ser. No. 574,489, Mar. 28, 1956, now PatentNo. 2,926,478, dated Mar. 1, 1960 Divided and this application May 11,1961, Ser. No. 109,380 '3 Claims. (CL 180-65) The present inventionrelates to lawn mowers, and, more specifically, to power lawn mowers ofthe type in which a suitable prime mover is associated with the lawnmower to drive the cutting mechanism. Specifically, the presentapplication is a division of application Serial No. 825,255, filedJu'ly6, 1959, now Patent No. 3,028,719, which in turn, is a division ofparent application Serial No. 574,489, filed March 28, 1956, now PatentNo. 2,- 926,478.

In recent years there has been a tremendous increase in the demand forpower lawn mowers. This has been brought about for several reasons.First of all, with the high cost of labor, the householder finds itdifiicult to get help to mow lawns, and, secondly, the power operatedlawn mower has been made available at prices which make it attractive tothe ordinary householder. As a matter of fa-ct, at the present time morethan a million power operated lawn mowers are sold every year.

Power operated mowers employing an electric mot-or as the prime moverthereof, unless a battery or other self-contained source of electricenergy is connected to the motor, require connection with an externalsource of electrical energy, and consequently require a power cord ofsubstantial length to permit mowing a lawn of any size. It would bedesirable to provide an electric motor driven power lawn mower in whichthe problem of handling a mowing operation without cutting the cord iscompletely eliminated. A power operated lawn mower should also berelatively light in weight so that it can be handled without difficultyby women. Consequently, it would be desirable to provide a simpleconstruction having relatively few parts, of lightweight material, thusproviding a lightweight device and furthermore insuring a device whichwill give long years of trouble-free service.

Although it is generally not desirable to mow lawns when the grass iswet, sometimes this becomes necessary due to weather conditions whichare not conducive to satisfactory lawn mowing. It is common practice forpower opera-ted lawn mowers to be supported on suitable wheels providedwith rubber tires, thereby doing a minimum amount of damage to the lawnsurface. However, such rubber tires insulate the mower structure fromthe ground, and if there should be some damage to the electricalcircuit, the source voltage or at least some leakage current might beapplied to the lawn mower. It would be desirable in a power operatedlawn mower having rubber-tired wheels to assure grounding of the mowerstructure at all times whenever the mower is supported from the wheels,thus eliminating any shock.

Accordingly, it is an object of the present invention to provide a newand improved power operated lawn mower having the desirable feature setforth above.

It is a further object of the present invention to provide a poweroperated lawn mower supported on rubber-tired wheels in which improvedmeans for grounding the mower are provided.

Further objects and advantages of the present invention will becomeapparent as the following description proceeds, and the features ofnovelty which characterize the invention will be pointed out withparticularity in the claims annexed to and forming a part of thisspecification.

*For a better understanding of the present invention, reference may behad to the accompanying drawings in which:

FIG. 1 is a perspective view of a power operated lawn mower built inaccordance with the present invention with the wheels adjusted formaximum height of cut;

FIG. 2 is a bottom view of the lawn mower of FIG. 1;

FIG. 3 is an enlarged inverted sectional view taken on line 3-3 of FIG.2 but with the wheel shown in the posithe wheels adjusted for maximumheight of cut;

FIG. 4 is a sectional view taken on line 4-4 of FIG. 3.

Briefly, the present invention is concerned with a lightweight, electricpowered lawn mower. The lawn mower is provided with improved means toground the platform even though supported on rubber-tired wheels.

Referring now to the drawings, there is illustrated a lawn mower,generally indicated at 20, which comprises a carriage 21, including ahousing or support 22 suitably supported on ground wheels 23. Mounted onthe carriage 21 is a prime mover, generally designated as 25,specifically indicated as an electric motor. For the purpose of guidingthe carriage, there is included a handle assembly, generally designatedat 26, which handle assembly is pivotally associated with the carriage21.

The details of the power operated lawn mower are fully disclosed inPatents Nos. 2,926,478 and 3,028,719 from which this application isderived, and the disclosures of those patents are incorporated herein byreference.

For the purpose of supporting the carriage 21 for movement over the areato be mowed, the housing 22 is provided with integral arms projectingfrom what might be called the four corners thereof. As a matter of fact,the arms designated as 31, 32, 33 and 34 elfectively define four cornersof the housing 22. The wheels 23 are secured one to each of therespective arms 31, 32, 33 and 34 by suitable wheel axle bolts 35 andassociated nuts 36, best shown in FIGS. 3 and 4 of the drawings. Asthere illustrated, each arm such as 34, for example, is provided with arecess 38 within which are provided a plurality of vertically spacedopenings 39 for receiving the associated wheel axle bolt 35..

As best shown in FIG. 4 of the drawings, each wheel 23 is provided witha centrally disposed wheel axle sleeve 40 serving as a suitable bearingto receive the associated Wheel axle bolt 35. Preferably and asillustrated, the wheels 23 are provided with rubber tires indicated at41, thus providing an arrangement which is relatively noiseless whenmoving on a hard surface such as a sidewalk and which will do a minimumof damage to a lawn, and which furthermore also provides a pleasingappearance.

To "operate electric motor 25, it is, of course, necessary to connectelectrical power thereto. To this end there is provided a power cord 104which preferably enters the motor housing through an opening in the topof the cover 100.

In order that any damaged insulation to the power cord which might causethe line voltage to be applied to the mower 20 will not result in anelectrical shock to the operator, means are provided to insure that thelawn mower 20 is grounded at all times. To this end a grounding wire isprovided for two of the wheels 23, preferably diagonally positionedwheels. Thus, as is clearly shown in FIGS. 1, 2, 3 and 4 of thedrawings, a grounding wire is disposed in a groove in the associatedtire 41 so as to project beyond the periphery of the tire and always bein engagement with the ground. Preferably, the grounding wire 150 hasthe ends thereof projecting laterally through an opening in the tire andthe wheel, as designated at 150a, in FIG. 3 of the drawings. The ends ofthe lateral projections 150a extending through the wheel are furtherdeformed laterally as indicated at 15% so as to make eleclrical contactwith the wheel 23, which, of course, is electrically connected throughthe metal connections with the lawn mower proper. Thus, with thisarrangement, even though a rubber-tired mower is employed, asatisfactory ground is always assured. By employing the grounding wireon two wheels diagonally mounted on the mower, such grounding connectionis insured even though the front end or the back end of the mower istipped up, which is sometimes necessary when going over curbs or thelike. Preferably, the grounding wire 150 is formed of stainless steel.With this arrangement the operator need not worry about a short circuitand resultant shock if the mower is left out in the rain. There is nodanger of even a slight shock which is common with other electric lawnmowers.

The operation of the present invention will readily be understood, inView of the detailed description included above, and no furtherdiscussion is included herewith.

While there has been illustrated and described what is at presentconsidered to be a preferred embodiment of the present invention and asingle modification thereof, it will be appreciated that numerouschanges and modifications are likely to occur to those skilled in theart, and it is intended in the appended claims to cover all thosechanges and modifications which fall within the true spirit and scope ofthe present invention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. A lawn mower comprising a carriage, a plurality of wheels supportingsaid carriage, resilient electrical insulating material defining tiresfor each of said wheels, an electric motor supported on said carriage, apower cord connected to said motor for energizing said motor from asource of electrical energy, conducting means comprising a wire ringencompassing the circumference of at least one of said tires and securedthereto so that said ring is in continuous engagement with a supportingsurface when said one tire is rotated in response to normal movement ofsaid carriage over said surface, and means for electrically connectingsaid conducting means to said carriage whereby any electrical potentialapplied to said carriage by virtue of said power cord is grounded tosaid supporting surface through said conducting means.

2. The Lawn mower of claim 1 wherein said tire is provided with acircumferential groove and said wire ring is disposed within said groovebut projecting above the surface of said tire defining the maximumcircumference thereof.

3. The lawn mower of claim 1 wherein two pairs of wheels are providedand said conducting means is applied to two wheels comprising adifferent one of each pair.

References Cited by the Examiner UNITED STATES PATENTS 913,943 3/1909Brown 280-4734 1,411,998 4/1922 Grace et a1 19163 X 1,545,672 7/1925McArthur 317--2 1,797,545 3/1931 Churcher 15L2151 1,859,343 5/1932 Rouge152-151 1,868,347 7/1932 Cloud 5625.4 2,074,958 3/ 1937 Chirelstein339105 2,309,741 2/1943 Woodward 339l05 2,524,163 10/1950 Criss 191-1 X2,535,457 112/1950 Roberts 280-4734 2,559,897 7/1951 Phelps 56--25.4

A. HARRY LEVY, Primary Examiner. CARL W. ROBINSON, PHILIP ARNOLD,Examiners.

UNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,217,824 November 16, 1965 Ivar Jepson It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

In the grant line 3, after "Illinois," insertassignor to SunbeamCorporation, of Chicago, Illinois, a corporation of Illinois, line 12,for "Ivar Jepson, his heirs" read Sunbeam Corporation, its successors inthe heading to the printed specification, line 4, for "Ivar Jepson, 547Linden Ave. Oak Park, Ill read Ivar Jepson, Oak Park, Ill. assignor toSunbeam Corporation, Chicago, Ill. a corporation of Illinois Signed andsealed this 10th day of January 1967.

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner ofPatents

1. A LAWN MOWER COMPRISING A CARRIAGE, A PLURALITY OF WHEELS SUPPORTINGSAID CARRIAGE, RESILIENT ELECTRICAL INSULATING MATERIAL DEFINING TIRESOF EACH OF SAID WHEELS, AN ELECTRIC MOTOR SUPPORTED ON SAID CARRIAGE, APOWER CORD CONNECTED TO SAID MOTOR FOR ENERGIZING SAID MOTOR FROM ASOURCE OF ELECTRICAL ENERGY, CONDUCTING MEANS COMPRISING A WIRE RINGENCOMPASSING THE CIRCUMFERENCE OF AT LEAST ONE OF SAID TIRES AND SECUREDTHERETO SO THAT SAID RING IS IN CONTINUOUS ENGAGEMENT WITH A SUPPORTINGSURFACE WHEN